fadderTackFest

(*
	REPRESENTATION CONVENTION: 	Beer(n): n amount of beer.
	REPRESENTATION INVARIANT: 	Evidently the best beverage in the world.
*)
datatype beer = Beer of int

(*
	REPRESENTATION CONVENTION: 	Datavetare(dvname, drunkenbeer):
					A computer scientist with the name dvname
					and the amount of beer drunk, drunkenbeer.
	REPRESENTATION INVARIANT: 	Probably the most 1337 student in the world.
*)
datatype datavetare = Datavetare of string * beer

(*
	REPRESENTATION CONVENTION: 	Fadder(dv): A dv full of wisdom.
	REPRESENTATION INVARIANT: 	No flaws.
*)
datatype fadder = Fadder of datavetare

(*
	REPRESENTATION CONVENTION: 	Etta(dv): A dv full of noobiness.
	REPRESENTATION INVARIANT: 	Too many to count.
*)
datatype etta = Etta of datavetare

(*
	REPRESENTATION CONVENTION: 	Party(f, e): An awesome gathering of faddrar f and ettor e.
	REPRESENTATION INVARIANT: 	Preferably drunkenbeer >= 10 for every etta in e and
					drunkenbeer >= 20 for every fadder in f.

*)
datatype party = Party of (fadder list * etta list)

(*
	REPRESENTATION CONVENTION: 	Wasted(dv): A dv as wasted.
	REPRESENTATION INVARIANT: 	Crave for munchies,
					no self-control,
					no manners,
					memory loss,
					money loss,
					unwanted fluids,
					unwanted home runs,
					unwanted tomorrow.
*)
datatype wasted = Wasted of datavetare

(*
	emptyFadderList
	TYPE: 		'a list
	VALUE: 		An empty (soon to be filled) list of faddrar.
*)
val emptyFadderList = []

(*
	emptyEttaList
	TYPE: 		'a list
	VALUE: 		An empty (soon to be filled) list of ettor.
*)
val emptyEttaList = []

(*
	addFadder(l, n)
	TYPE:		fadder list * string -> fadder list
	PRE:		n is a real fadder.
	POST:		l with another awesome fadder n.
	EXAMPLE: 	addFadder(emptyFadderList, "Märta") =
			[Fadder (Datavetare ("Märta", Beer 0))]: fadder list
*)
fun addFadder(l, n) = Fadder(Datavetare(n, Beer 0))::l

(*
	addEtta(l, n)
	TYPE:		etta list * string -> etta list
	PRE:		n is a real etta.
	POST:		l with another noob n.
	EXAMPLE: 	addEtta(emptyEttaList, "Mitra") =
			[Etta (Datavetare ("Mitra", Beer 0))]: etta list
*)
fun addEtta(l, n) = Etta(Datavetare(n, Beer 0))::l

(*
	mkPartyList(f, e)
	TYPE:		fadder list * etta list -> party
	PRE:		(none)
	POST:		f and e together as an awesome party.
	EXAMPLE: 	mkPartyList([Fadder (Datavetare ("Märta", Beer 0))],
			[Etta (Datavetare ("Mitra", Beer 0))]) =
			Party ([Fadder (Datavetare ("Märta", Beer 0))],
			[Etta (Datavetare ("Mitra", Beer 0))]): party
*)
fun mkPartyList(f, e) = Party(f, e)

(*
	moreBeer(p, b)
	TYPE:		party * beer -> party
	PRE:		(none)
	POST:		Adds b to drunkenbeer for every etta in p and
			b*2 to drunkenbeer for every fadder in p.
	EXAMPLE: 	moreBeer(Party ([Fadder (Datavetare ("Märta", Beer 0))],
			[Etta (Datavetare ("Mitra", Beer 0))]), Beer 1) =
			Party ([Fadder (Datavetare ("Märta", Beer 2))],
			[Etta (Datavetare ("Mitra", Beer 1))]): party
*)
fun moreBeer(Party(f, e), Beer n) =
	let
		(*
			beerToEtta e
			TYPE:		etta list -> etta list
			PRE:		(none)
			POST:		Adds one (1) beer to drunkenbeer for every etta in e.
			EXAMPLE: 	beerToEtta([Etta (Datavetare ("Mitra", Beer 0))]) =
					[Etta (Datavetare ("Mitra", Beer 1))]: etta list
		*)
		(*VARIANT length e*)
		fun beerToEtta([]) = []
		| beerToEtta(Etta(Datavetare(s, Beer b))::xs) =
			Etta(Datavetare(s, Beer(b+n)))::beerToEtta(xs)
		(*
			beerToFadder f
			TYPE:		fadder list -> fadder list
			PRE:		(none)
			POST:		Adds two (2) beers to drunkenbeer for every fadder in f.
			EXAMPLE: 	beerToFadder([Fadder (Datavetare ("Märta", Beer 0))]) =
					[Fadder (Datavetare ("Märta", Beer 2))]: fadder list
		*)
		(*VARIANT length f*)
		fun beerToFadder([]) = []
		| beerToFadder(Fadder(Datavetare(s, Beer b))::xs) =
			Fadder(Datavetare(s, Beer(b+2*n)))::beerToFadder(xs)
	in
		Party(beerToFadder(f), beerToEtta(e))
	end

(*
	checkParty(p)
	TYPE: 		party -> bool
	PRE:		(none)
	POST:		True if drunkenbeer >= 10 for any etta in party, else false.
	EXAMPLE: 	checkParty(Party ([Fadder (Datavetare ("Märta", Beer 2))],
			[Etta (Datavetare ("Mitra", Beer 1))])) = false: bool
*)
fun checkParty(Party(_, [])) = false
| checkParty(Party(f, Etta(Datavetare(s, Beer b))::xs)) =
	if b >= 10 then
		true
	else
		false

(*
	fadderTackFest(people, b)
	TYPE: 			party * beer -> wasted list
	PRE: 			b >= 10
	POST: 			party people as wasted when number of beer b are more than 10.
	EXAMPLE: 		fadderTackFest(Party ([Fadder (Datavetare ("Märta", Beer 0))],
				[Etta (Datavetare ("Mitra", Beer 0))]), Beer 10) =
				[Wasted (Datavetare ("Märta", Beer 20)),
				Wasted (Datavetare ("Mitra", Beer 10))]: wasted list
*)
(*TIME COMPLEXITY: Θ (b) always*)

fun fadderTackFest(party as Party(f, e), Beer b) =
	let
		exception notEnoughBeer

		val partyparty = moreBeer(party, Beer b)

		(*
			wastedEtta e
			TYPE:		etta list -> wasted list
			PRE:		(none)
			POST: 		e as wasted.
			EXAMPLE:	wastedEtta([Etta (Datavetare ("Mitra", Beer 10))]) =
					[Wasted (Datavetare ("Mitra", Beer 10))]: wasted list
		*)
		(*VARIANT length e*)
		fun wastedEtta([]) = []
		| wastedEtta(Etta(dv)::xs) =
			Wasted(dv)::wastedEtta(xs)
		(*
			wastedFadder f
			TYPE:		fadder list -> wasted list
			PRE:		(none)
			POST: 		f as wasted.
			EXAMPLE:	wastedFadder([Fadder (Datavetare ("Märta", Beer 20))]) =
					[Wasted (Datavetare ("Märta", Beer 20))]: wasted list
		*)
		(*VARIANT length f*)
		fun wastedFadder([]) = []
		| wastedFadder(Fadder(dv)::xs) =
			Wasted(dv)::wastedFadder(xs)
		(*
			fadderTackFest' people
			TYPE:		party -> wasted list
			PRE:		(none)
			POST: 		party people as wasted.
			EXAMPLE:	fadderTackFest'(Party ([Fadder (Datavetare ("Märta",
					Beer 20))], [Etta (Datavetare ("Mitra", Beer 10))])) =
					[Wasted (Datavetare ("Märta", Beer 20)),
					Wasted (Datavetare ("Mitra", Beer 10))]: wasted list
		*)
		fun fadderTackFest'(Party(f', e')) =
			if checkParty(partyparty) = true then
				wastedFadder(f')@wastedEtta(e')
			else
				raise notEnoughBeer

	in
		fadderTackFest'(partyparty)
	end;


(* Test cases for fadderTackFest. *)
let
	val fadderList = addFadder(emptyFadderList, "Märta")
	val ettaList = addEtta(emptyEttaList, "Mitra")
	val party = mkPartyList(fadderList, ettaList)
	val fadderTackFest = fadderTackFest(party, Beer 10)
	val expectedResult = [Wasted (Datavetare ("Märta", Beer 20)),
	Wasted (Datavetare ("Mitra", Beer 10))]
in
	print("\n\nTest case for upcoming fadderTackFest:\n");
	(1, fadderTackFest = expectedResult)
end